Nesting software: A tool for lean manufacturing

WWW.THEFABRICATOR.COM MARCH 2008

March 11, 2008

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Nesting software can help make your operation leaner. Software advancements have automated many processes. This article discusses the latest software features to consider when selecting the right program for your operation. Among these is the ability to nest a partial sheet or plate and then save the digital remnant or skeleton for later use.

ProNest 8 Software Screenshot

What Is Nesting Software?

In general terms, nesting software automatically and efficiently arranges the required quantities of individual parts to be produced on sheets or plates of stock material. It does this by using part geometry from CAD files to output NC code that controls a cutting machine, such as a laser, plasma, oxyfuel, waterjet, or saw.

The History of Nesting Software

Before the advent of PCs (personal computers, also known as microcomputers for those old enough to remember), cutting machines were programmed using lengths of perforated tape generated by mainframe computers. In the early 1980s, when CNC for cutting machines became available and the PC became more commercially viable, their business use began to flourish, and the idea of developing nesting software to run on a PC platform was born. The core objective for nesting software was to leverage the mathematical processing power of the PC to optimize material usage and reduce cost.

Nesting Software Today

Today's nesting software is much more sophisticated than initial versions, and its role in lean manufacturing has grown significantly. Although optimizing material use still is a critical task, nesting software now plays additional roles in three other areas: integration, automation, and part quality. For example, nesting software now can:

  • Work easily with all standard 2-D and 3-D CAD formats.
  • Link to a central material inventory and work order database.
  • Create highly optimized nests of all materials and thicknesses within a single job.
  • Automatically decide which full sheets or remnants provide the best material utilization for a given job.
  • Create complex NC code that integrates all cutting machine components.
  • Cut better parts.

Selecting Nesting Software

Typical functionality of nesting software and some items to consider when making a purchase decision are:

CAD Import—Until recently the CAD world was flat, using 2-D file formats such as DXF, and DWG. Most, if not all, nesting software programs are able to import and work with these file types. Some programs also can automatically flatten 3-D part and assembly files developed in programs such as SolidWorks®, Inventor®, and ProEngineer®, which eliminates the manual intermediate step of producing 2-D files. Nesting programs with automatic CAD error correction tools and tool-pathing capability provide additional automation during the CAD import process.

Process Parameters—To achieve optimum part quality, nesting software may be used to apply advanced process-specific parameters. The parameters that need to be applied depend on the cutting process used. With a plasma machine, for example, varying the feed rate and kerf compensation and enabling automatic height control lockouts are just some of the factors that need to be implemented to achieve good-quality holes. A laser machine may require the activation of a pulse pierce with a proper cut condition.

Nesting software should be able to provide specific settings for many holes of varying sizes. Cutting sharp corners with a waterjet machine requires a ramp-down of the cutting speed going into the corner and a ramp up coming out of the corner. On the other hand, lasers may benefit from specific corner-radiusing techniques to achieve the same goal. Whatever the objective may be, nesting software is available to provide the power and flexibility needed for a given cutting process.

Automatic Nesting—Nesting software began with basic manual nesting. Programmers moved shapes around on an imaginary sheet to achieve the best possible material utilization. Although this process still has a place today, in most circumstances, advanced mathematical algorithms now are employed to create highly efficient nests automatically, including space-saving techniques such as part-in-part void filling and look-ahead logic. Advanced nesting systems allow for and alter nesting techniques based on an assortment of variables, such as material type, thickness, clamping, and repositioning requirements.

Productivity Tools—Creating highly efficient nests is one thing, but cutting those nests productively is another. Thanks to many productivity tools now incorporated within nesting software, manufacturers can cut their nests faster and smarter than ever before. As with process parameters, different cutting processes may benefit more from productivity tools than others. Whether used with common-line cutting to reduce cutting time on a waterjet, collision avoidance to prevent part tip-ups on a laser, or chain cutting to eliminate costly preheat cycles on an oxyfuel machine, nesting software offers a variety of beneficial features, no matter what the cutting process.

Material and Inventory Optimization Tools—Lean manufacturing involves turning over material inventory as often and as completely as possible. Nesting software plays a key role in this process. A very useful tool is the ability to nest a partial sheet or plate and then save the digital remnant or skeleton for later use with another nesting job. Such systems require a facilitywide commitment to inventory control, but can yield excellent material savings. Not all material remnants are conveniently stored in digital format, however, so the ability to use nesting software to create the remnant or import it as a CAD drawing is very useful and helps get those small but valuable "drops" out of the rack.

Not all material is defect-free, especially in the world of waterjet cutting, in which materials such as stone are routinely used. Importing a JPG image of the material over the electronic nest area and then nesting around voids and other defects to minimize scrap and wasted production time is yet another example of how advanced nesting software can help manufacturing companies succeed.

Tool Path—Generating an optimized tool path for the nest is a goal for every job, but the specific objective may vary based on cutting process and application. Accounting for these variables among the major cutting processes is an important function of nesting software. Intelligent sequencing at the nest and part level can reduce unnecessary production downtimes, reduce heat distortion issues, and help minimize plate warping. Automated lead-in/-out styles and positioning also assist with common problems such as poor part quality, part movement, and head crashes.

NC Output—It goes without saying that a primary function of any nesting software is to create a proper NC file that will allow functional code to be sent to the cutting machine. Ideally, the software should support all of the machine functionality necessary to automate production as much as possible.

The high-end plasma cutting machine market serves as a great example for this kind of automation. The core components of a plasma cutting machine are the CNC, plasma power supply, and automatic torch height controller. Running this equipment manually can be a lengthy process that consumes valuable machine time. However, many of these components now can be integrated and, with the correct NC output, automated. A nested file containing material type, thickness, amperage, and cut/shield gas information can be sent to the CNC, which in turn relays instructions to the power supply and automatic torch height controller on how the job should be cut. This type of automation not only saves time, but also ensures consistent part quality and reduces processing errors by eliminating unnecessary decision-making on the shop floor.

Management Reporting—Understanding what is going on in a company's production operation is important to lean manufacturing, whether it be related to capital equipment purchase, staffing issues, and so forth. Nesting software that offers quality reporting, including nest utilization, production time, part, and job costing, and inventory status, can make production more visible. Part and plate traceability via traditional labels and bar codes also is available with some programs.

Business System Integration—The icing on the cake for most nesting software users is how today's systems can integrate seamlessly with other corporate business systems on a companywide level. Leveraging modern data exchange technologies, nesting software can connect to ERP and MRP systems and significantly contribute to a lean manufacturing business approach.

The Path Ahead

Nesting software has come a long way over the years, and today a variety of programs are available, from basic systems to highly advanced. Integrating the software with other business systems can empower the software and allow it to become the heart of a fabrication or material processing operation.



Hypertherm

Derek Weston

Contributing Writer
Hypertherm
22 West Main St.
Lockport, NY 14094
Phone: 716-434-3755

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